1. Acoustic
2. Acquisition
3. Alkanes
4. Alumino-silicates
5. Amplitude anomaly
6. Anhydrite
7. Appraisal
8. Architectural element
9. Basin
10. Biogenic
11. Biomarker
12. Bitumen
13. Borehole
14. Carbon Cycle
15. Cavings
16. Commercial well
17. Connate water
18. Crude oil
Relating to sound waves (synonymous with Sonic)
Usually, in geophysics, the shooting of seismic data
Naturally-occurring paraffin fractions in which the
molecules are based on a "straight chain" of
hydrogen - saturated carbon atoms.
Minerals consisting mainly of Aluminium, Oxygen
and Silicon
Anomalous seismic amplitudes which may be
indicators of hydrocarbon or depositional
geological features.
An evaporite mineral, CaSO4, found in sedimentary
rocks; associated with gypsum.
Activity, such as a well drilled to confirm the size
or quality of a hydrocarbon discovery. Before
development, a discovery is likely to need at least
two or three such wells
a genetic unit in fluvial sediments.
1. A syn-depositional depression in the earth's
surface, typically, of a large size and
filled with sedimentary rocks.
2. Bowl-shaped synform in which layering dips
inward towards a central point.
A term applied to material produced by the action
of living organisms
Geochemical molecules, extracted from source
rocks or oils that can be used as an indicator of the
type of source organic matter (e.g., plant or animal)
and as a tracer for oil-to- source rock correlations.
A form of heavy, solid petroleum
A well, especially referring to the face of the
rock outside or below the casing. Test boreholes
are also sunk to examine the suitability of a site
formajor foundation work, and to examine
geological formations at points where no
hydrocarbons are expected.
The cycle of carbon on the planet: Fixed in living
organisms, burial of carbon in organic matter,
cooking and release into hydrocarbons, discov ery
through exploration, petroleum resource exploitation
and release into the atmosphere before being fixed
again in living organisms.
Large cuttings usually a sign of borehole
instability
A well capable of producing profitably
The original water content of a reservoir rock.
Connate water reduces the pore-space (porosity)
available to hydrocarbons. Sometimes called
Interstitial Water.
An unrefined mixture of naturally-occurring
hydrocarbons. Because it is essentially a mixture,
the density and properties of Crude Oil vary widely.
Light Crude normally has an A.P.I, gravity of 30° or
more. Gravities of 20° to 30° include the medium
gravity Crudes, while those below 20° are known as
Heavy. Heavy Oils are found right down to the
residual solid state. Sour crude has a significant
19. Crystal
20. Dead oil
21. Depth map
22. DHI
23. Dilation
24. Dry gas
25. Dry hole
26. Erosion
27. Evaporite
28. Exploitation well
29. Fat oil/Lean oil
30. Fault
31. Fish/fishing
32. Gas Condensate
sulphur content, low-sulphur crude is described as
Sweet.
A three-dimensional material (usually natural), the
bounding surfaces of which are arranged
symmetrically and, for a given substance, with
constant angular relationships, arising from the
inherent regular atomic structure of the substance.
Oil containing no natural gas
A relief map of a sub-surface geological structure
where the contours relate to depths from the
surface datum level, (i.e. sea level). This is a
further interpretation of a seismic time map.
Direct hydrocarbon indicators are seismic
anomalies that may indicate the presence of
hydrocarbons. Amplitude anomalies are often flat
("flat spots") or bright ("bright spots") and
associated with gas. "Gas chimneys" are sometimes
observed above oil fields and are expressed as a
series of anomalies in a plume over the field
attributed to gas leakage.
Increase in volume
Natural gas, methane and ethane, without any
significant content of heavier hydrocarbon fractions.
A well in which no hydrocarbon is found.
That part of the process of denudation which involves
the wearing away of the land surface by the
mechanical action of transported debris. The agents of
transportation are by themselves only capable of
minute wearing action upon the rocks, but when they
contain particles of weathered material they become
powerful agents of destruction
A deposit resulting from the evaporation of saline
water
A development well e.g. an oil or gas producer, or
gas or water injector to support production.
Saturated or under-saturated oil. "Fat" Oil could, for
example, be saturated with gasolines absorbed from
a gas stream in a refinery. The oil is "lean" when the
gasolines have been distilled out again, and the oil
recycled to the process
A fracture in rock along which there has been an
observable amount of displacement. Faults are
rarely single planar units; normally they occur as
parallel to sub-parallel sets of planes along which
movement has taken place to a greater or lesser
extent. Such sets are called fault or fracture-zones.
Any unwanted object down a well, commonly the
lower end of a drill string which has broken off.
"Fishing" is trying to recover the Fish, using
various attachments to the drill stem or wireline,
known as fishing tools.
Light hydrocarbon fractions entrained in gas
production which condense into liquid when
brought to the surface. Changes in reservoir
pressures as result of production may cause it to
condense in the reservoir, when much of it may
33. Gas oil
34. Gas/oil ratio (GOR)
35. Geochemical Analysis
36. Geological modelling
37. Geophones
38. Heat flow
39. Heavy mineral, Heavy mineral
separation
40. Horizontal drilling
41. Hydrocarbon minerals
42. Hydrodynamic
43. Improved Oil Recovery (IOR)
44. Inert gas
45. Inhibited mud
46. Interpretation
47. Isotopes
become irrecoverable.
A middle distillate product fraction
The proportional amount of gas to oil liquid
occurring in production from a reservoir, usually
expressed as cubic feet per barrel.
1. Analysis of the hydrocarbon-bearing potential
of an area by studying shallow cores and
subsurface water for evidence of seepage or
kerogens.
2. Analysis of cuttings for source rocks (e.g.
Headspace gas and vitrinite reflectance)
Computer modelling of the subsurface geology,
usually for input into the Reservoir simulator
Sound wave receivers employing a moving coil, used
primarily for onshore seismic surveys. Geophones
can also be clamped in wells.
The rate of heat crossing a horizontal plane. Generally
produced the inner zones of the Earth, but also by
radiation processes in the crust. The average value
is 65 mW/m2 per second, but higher values have
been recorded in certain localities (especially in
some areas of the ocean basins), which it is
suggested may be due to uprising convection
currents in the mantle.
By use of a heavy liquid a mixture of mineral
grains of different densities may be separated into
two fractions: those which sink, the 'heavy
minerals', and those which float, the 'light minerals'.
Usually refers to minerals whose density is greater
than 3.0gm/cc.
A technique for deviating wells through up to 90°
from the vertical. While the main purpose of
normal deviated drilling is to "reach" remote parts
of a reservoir, with horizontal drilling the purpose
is to keep the well bore within a given productive
horizon or formation, to increase potential
productivity
A term usually taken to mean the naturally occurring
solid varieties of carbon-hydrogen (sometimes also
with oxygen) compounds, i.e. the natural 'organic'
minerals. Two groups may be recognised - coal, and
the bitumens, waxes and resins
Active movement of water in the earth's crust
Any mechanism (e.g. Infill drilling, Horizontal
drilling) that improves oil recovery.
Chemically unreactive gases used to flood
compartments where there is fire or imminent
danger of fire. Inert gases are also used in the
mixture breathed by divers.
Mud containing chemicals to prevent loss of water
which could damage surrounding formations, and
cause build up of filter-cake in the well
Picking the seismic lines, identifying key horizons
and faults, generating maps. Generally refers to a
process of synthesising a conceptual model.
Chemical elements of same composition but
48. Jack-up
49. Kerogen
50. Log/logging
51. Magnetic field
52. Magnetic survey
53. Natural depletion
54. Oil spill
55. Petroleum play
56. Polarity
57. Pressure solution
58. Production Logging Tool (PLT)
59. Production testing
different atomic weight. Isopoes differ by unit
numbers of neutrons or protons.
Drilling rigs, production barges, etc. which once
floated onto location can raise themselves clear of
the water by 'jacking' themselves up their legs.
They then offer the operating advantages of fixed
platforms but unlike piled steel structures, their
stability and load capacity depends on the strength
and stability of the sea bed, and closely
underlying strata.
A solid organic material (lipid rich) which yields
petroleum-type hydrocarbons on heating and
distillation. Kerogen has labile and refractory
active proportions - the former sources oil, the
latter gas.
1. Written chronological records such as shift logs,
maintenance logs, tour sheets ,and mud logs which
also record the cuttings recovered from a well
.Various devices (tools) for taking measurements of
formations, physical conditions, and fluids
encountered by a well, together with the records
produced by them. The main types of well logs are
Electrical, Magnetic, Mechanical, Sonic, Nuclear,
Imagecollectively known as Wireline logs. (Tools and
Logs are usually recognized by initials e.g. CNT
and CNL - compensated neutron tool and log).
The Earth has a magnetic field, the poles of which
are close to the North and South Poles. The
magnetic field has reversed during the geological
past, although the mechanism for this is not well
understood.
A preliminary exploration technique based on the
relatively low-intensity magnetic fields associated
with sedimentary rocks.
Producing a reservoir by means of its natural
pressure - without pressure maintenance.
Any accidental emission of liquid hydrocarbons,
from general shipping, oil tankers, or operations
onshore or offshore.
A perception or model of how a specific region of
the Earth's sub surface may be an appropriate target
for exploration drilling. Requires knowledge of
source rock, maturity, timing, reservoir, migration,
trap, seal. The play chance is the probability of a
successful exploration well.
Positive (black) or negative (white) parts of a wave used in the presentation of seismic sections, hence,
reverse polarity.
Deformation mechanism that involves dissolution
at grain boundaries under stress of soluble
constituents such as calcite or quartz. Generally
active at low to moderate temperature in the
presence of water
A combination of temperature log and spinner to
locate the entry point of fluids into the bore hole.
A production test concerns the capability to produce
60. Productivity/productivity index (PI)
61. Profiling
62. Proprietary data
63. Provenance
64. PVT
65. P-waves
66. Pyrolysis
67. Quartz
68. Radioactive decay
69. Radiometric dating
70. Radiocarbon dating
71. Raw gas
72. Recrystallisation
73. Red beds
74. Remigration
75. Reserves
(productivity) of a well and its effects on the
reservoir produced. A production test may continue
for several months where extensive data is
necessary prior to final commitment to
development expenditures etc.
The continuous productive capacity of a well. The
Index is measured as volume produced (e.g. barrels
per day) divided by the drop in pressure to achieve
that flow rate starting with a "shut in" pressure.
Shallow seismic surveying by echosounder
techniques
Primarily data obtained from the owner of a seismic
survey record under confidentiality undertaking. It
can also include all confidential information
acquired as part of sole or joining operations
The source area or areas of the material making up
a sediment, more especially the nature of the rocks
from which the material has been derived. PST:
Production Sample Taker - for accurate
identification of fluids produced by a given zone in
the well.
Pressure/Volume/Temperature data usually related
to a test of a reservoir formation or well.
Compressional, longitudinal pressure or primary
waves
Burning of rock in the lab to determine the oil yield
of a rock as in the Rock Eval wellsite technique
a silicon mineral (Si 0 2) that makes up most of
sand (see Sandstone, silicates)
The natural decay of nucleides by the emission of
atomic particles (e.g., Rubidium to Strontium).
Used for Radiometric dating.
Method for determining the absolute age of rocks (see
Rub idium-Strontium) by the radioactive decay of
nucleides.
Age dating by the measurement of the decay of
carbon isotopes (a form of Radiometric dating).
Natural gas before removal of water, sand and
other impurities
The process whereby amass of crystals passes
through a solution phase in developing a new set of
crystals of the same kind
A term applied to an assemblage of sedimentary
rocks formed in a highly oxidising environment, so
that the iron present is in the form of red ferric
hydroxide. The term has acquired a meaning almost
synonymous with arid continental sediments, since
most red beds were probably formed in such an
environment. The meaning has also been extended
not only to the typical red sandstones, red shales
and red marls, but also to include associated
evaporites, breccias, and cornstones (concretionary
limestones).
Oil migrating out of a trap, due to breaching or
tilting
Reserves are estimated volumes of crude oil,
76. PROVED RESERVES
77. UNPROVED RESERVES
78. Reservoir
79. Residual oil
80. Rig
81. Rock-forming minerals
82. Sedimentary rocks
83. Seismic Method
84. Seismic reflection
condensate natural gas, natural as liquids, and
associated marketable substances anticipated to be
commercially recoverable and marketable from a
given date forward under existing ec onomic
conditions, by establi shed operating practices, and
under current go vernment regulations.
Proved reserves are attributed to known reservoirs
and are the least uncertain category. Proved reserves
have only a 10% chance of not being met
Unproved reserves may be subdivided into two
classifications: (1) Probable and (2) Possible
1. Probable Reserves: Probable reserves are
attributed to known accumulations and are based
on geologic and/or engineering data similar to
those used in estimates of
proved reserves; but technical, contractual, or
regulatory considerations preclude such volumes
from being classified as proved. Probable reserves
are more uncertain than
proved reserves with a 50% chance of being met
(P50).
2. Possible Reserves: Possible reserves are
associated with known accumulation sand
are based on geologic and/or engineering data that
are less complete and less conclusive than the data
used in estimates of probable reserves. In some
cases, contractual or regulatory uncertainties
may dictate the possible classification. Possible
reserves have a 90% chance of not being met
(P90) or only a 10% chance of being present.
A porous, fractured or cavitied rock formation with
a geological seal forming a trap for producible
hydrocarbons
The dense, viscous "Heavy Ends" of the barrel,
remaining after extraction of higher-value fractions
A collective term to describe the permanent
equipment needed for drilling a well. It has come to
include the onshore and offshore vehicles, mobile
platforms or vessels on which the equipment is
installed
Those minerals which occur in sufficient abundance
and frequency as to constitute the major bulk of a
rock. The main rock-forming minerals are the
silicates (including silica), carbonates, and oxides,
with sulphates, chlorides and phosphates in lesser
proportions.
An area which in a past geological era has been
depressed, acquiring deposits of sedimentary rocks
such as sandstones, siltstones or limestones. They are
formed from detritus or erosion etc. of exposed
formations and deposited in land or seabed
depressions, or as e.g. wind-formed desert dunes.
Acquisition, Processing, Interpretation and
Visualization
Acoustic (sound) waves, generated by explosives
or a mechanical vibrating truck (vibroseis),
85. Tectonics
86. Thermal recovery
87. Thief zone
88. Transition zone
89. Trap
90. Wash out
transmitted through the Earth, reflected where
velocity changes, and recorded by an array of
geophones.
1.The process of formation and evolution of the
earth's solid surface crust. "Plate
Tectonics" relates to the formation and movement
of the 'plates' of which the crust
is composed.
2.Study of large crustal ormantle features, such as
mountain ranges, parts of continents,
trenches and island arcs, oceanic ridges, mantle
plumes and entire continents and
ocean basins, and the relationships to stresses and
tectonic plates.
Enhanced Oil Recovery based on heating the oil in
the reservoir by steam injection or subsurface
combustion.
A porous, fractured or vuggy formation in a well,
into which drilling fluid escapes. It must be
plugged or lined with casing.
1.Part of the Mantle
2.Nearshore between land and marine - for seismic
acquisition
3.Above the OWC, the region where mobile water
is present
A structure in which oil and/or gas may collect
1.Water leaks into the drilling mud downhole.
2.Mud short circulates through a hole in the
drillstring.
3. Enlargement of the borehole to cavings